San Andreas Fault
The San Andreas Fault is a continental strike-slip fault that runs a length of roughly 810 miles (1,303.6 km) through California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. The fault's motion is right-lateral strike-slip (horizontal motion). It forms the tectonic
Tectonics is a field of study within geology concerned generally with the structures within the lithosphere of the Earth and particularly with the forces and movements that have operated in a region to create these structures.Tectonics is concerned with the orogenies and tectonic development of...

 boundary between the Pacific Plate
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate....

 and the North American Plate
North American Plate
The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, Bahamas, and parts of Siberia, Japan and Iceland. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust...


The fault was first identified in Northern California
Northern California
Northern California is the northern portion of the U.S. state of California. The San Francisco Bay Area , and Sacramento as well as its metropolitan area are the main population centers...

 by UC Berkeley
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...

 geology professor Andrew Lawson
Andrew Lawson
Andrew Cowper Lawson July 25,1861- June 16,1952 was a professor of geology at the University of California, Berkeley. He was the editor and co-author of the 1908 report on the 1906 San Francisco Earthquake which became known as the "Lawson Report"...

 in 1895 and named by him after a small lake which lies in a linear valley formed by the fault just south of San Francisco, the Laguna de San Andreas.